Challenge 7: Incorporating Multiple Inputs

Functions + Fish

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Download .qmd starter file

Download BlackfootFish.csv

This is a continuation of Lab 7: Functions + Fish.

library(tidyverse)
fish <- read.csv("BlackfootFish.csv")
Error in file(file, "rt"): cannot open the connection

A frequently used measurement for fish health is a condition index (Wikipedia article). The following simple equation can be used to calculate the approximate condition index of a fish:

\[\text{condition index} = \frac{weight}{length^3} \times 100\]

1. There are specific units required for the calculation of a condition index – length must be in centimeters and weight must be in grams. The weight data for the Blackfoot River fish were collected in grams; the length data were collected in millimeters. Transform the length data to the correct units.

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2. Replace impossible length and weight measurements with NAs. Do some research on the 4 species of trout included in these data to determine what measurements are unlikely or impossible. Write a function to handle this process.

Your function should accept at least three inputs:

If a value falls outside these bounds, you should replace it with an NA.

Tip

If you are struggling with the structure of your function, I would suggest reading the Mutating Function from R4DS.

Use your function to modify the length and weight columns of the BlackfootFish data set, removing values you believe are unreasonable.

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3. Write a function to calculate the condition index of a fish, given inputs of weight and length.

Warning

Consider whether your function will accept vectors as inputs or if it will accept variable names as inputs!

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4. Make a thoughtful visualization of how fish conditions have varied over the duration of this study.

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